C: capillaries are the smallest blood vessels that allow exchange of gases and nutrients.
<span>hope this helps!</span>
Explanation:
A) Carbon Dioxide is your answer,100%
Structural adaptations<span> are physical features of an </span>organism<span> like the bill on a bird or the fur on a bear. Other </span>adaptations<span> are behavioral. Behavioral </span>adaptations<span> are the things </span>organisms do<span> to </span>survive. For example, bird calls and migration are behavioraladaptations<span>.</span>